Work necessary to pump gasoline from a tank

hoganmadman
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Homework Statement


Suppose a large gasoline tank has the shape of a half cylinder 8 feet in diameter and 10 feet long. If the tank is full find the work (W) necessary to pump all the gasoline to the top of ht tank. Assume gasoline wights 42 pounds per cubic foot.


Homework Equations


W= ∫42(l-x)A(x)dx

The Attempt at a Solution


I know I'm suppose to find the crossectional area then which is A(x) and the the height to which i am pumping the oil. But my problem is i can't draw a picture of the problem and i m a visual learner. I tried having the bottom of the tank be at the origin and placing the y-axis at the radius of 4. Other than that i not sure where to start. Any help would be appreciated
 
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hoganmadman said:

Homework Statement


Suppose a large gasoline tank has the shape of a half cylinder 8 feet in diameter and 10 feet long. If the tank is full find the work (W) necessary to pump all the gasoline to the top of ht tank. Assume gasoline wights 42 pounds per cubic foot.


Homework Equations


W= ∫42(l-x)A(x)dx

The Attempt at a Solution


I know I'm suppose to find the crossectional area then which is A(x) and the the height to which i am pumping the oil. But my problem is i can't draw a picture of the problem and i m a visual learner. I tried having the bottom of the tank be at the origin and placing the y-axis at the radius of 4. Other than that i not sure where to start. Any help would be appreciated

Draw a picture of the end view of the tank, which has the shape of the lower half of a semicircle. I would put the origin at the center of the circle, so the the low point of the tank is at (0, -4).

You don't need a drawing of the whole tank; just the end view will do. The volume of liquid in the tank is the cross-sectional area A(x) times 10.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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